Method of roughening and dulling polyethylene terephthalate fibers



United fitates Patent 2,861,865 METHOD OF ROUGHENING AND DULLING POLYETHYLENE TEREPHTHALATE FIBERS Erhard Siggel, Laudenbach, Main, Germany, assignor to Vereinigte Glanzstoif-Fabriken A. G., Wuppertal-Elberfeld, Germany, a corporation of Germany No Drawing. Application August 2, 1954 Serial No. 447,381 Claims priority, application Germany August 3, 1953 7 Claims. (Cl. 1854) This invention relates to roughening and simultaneous dulling of fibers made of polyethylene terephthalate.

The instant invention makes it possible favorably to change the surface structure of the fibers or filaments and simultaneously to achieve a dulling thereof.

It is known that fibers produced by the conventional melt spinning of polyamides or of aromatic polyesters have a completely smooth surface. The disadvantage of the smooth surface of such fibers is the appearance of the so-called pilling-effect which occurs when the fibers are used for producing textile fabrics. The term pilling effect refers to the slow but continuous loosening of individual fibers from the surface of the fabric. The result thereof is a rolling together or intertwining or felting of the gradually protruding fibers in the form of knobs.

To prevent such undesirable formations on the surface 'of the fabrics made from polyamide fiber it has been proposed that, prior to manufacture of the fiber into textiles, the polyamide fiber be treated with monohydric or polyhydric alcohol solutions or with metallic salt solutions such as zinc chloride solutions or magnesium chloride solutions. However, fibers made of polyethylene terephthalate do not emerge satisfactorily from such after-treatments. On the other hand, it has been proposed that polyethylene terephthalate fibers be wetted with highly concentrated solutions of caustic soda. The result of such treatment is merely the production of a dulling effect. A reduction and much less an elimination of the pilling effect, cannot be obtained by that treatment.

It has been discovered that polyethylene terephthalate fibers may be simultaneously roughened and dulled by a novel after-treatment. To achieve this aim, polyethylene terephthalate containing from 5% to 30%, preferably 7% to 12% of the solvent, is spun in accordance with conventional techniques and the still warm fibers containing solvents are guided through a short distance in the air. The fibers are then conducted through an aftertreatment bath of organic liquids, the effect and purpose of which is to dissolve or extract the solvent contained in the outer layer of the fiber. Among the solvents which m y be employed in carrying out the solvent-condensation of ethylene glycol terephthalates, there are for example: diphenyl methane, diphenyl oxide, diphenyl,

benzophenone, alpha-methyl-naphthalene, etc., these sol- I vents being present in the poly condensates to the extent hereinabove mentioned.

Suitable agents or means for effectuating the aftertreatment are characterized by the feature that: (a) they do not dissolve polyethylene terephthalate fibers, but (7;) do possess the property of dissolving or extracting the aforesaid residual solvents present in the outer layer of the fibers. Among the agents possessing such characteristics are: carbon tetrachloride, tetrachloroethylene, acetone, tetrahydronaphthalene, etc.

By introducing the fibers while still in the warm condition into an after-treatment bath, a swelling of the fiber surface is etfectuated. Thereafter the fibers are subjected to the customary high stretching. The roughening and the dulling of the fiber surface is then accomplished by means of super-heated steam.

This technique is particularly advantageous when the 2,861,865 Patented Nov. 25, 1958 ICC residual solvent content of the fibers does not exceed 12% The following is an example of this invention.

Example Polyethylene terephthalate containing 10% of alphamethyl-naphthalene is spun by the conventional melt spinning method. The still warm, solvent-containing fibers after passing through a short air gap of about 10 centimeters, are conducted into an after-treatment bath consisting of coldcarbon tetrachloride. The fibers are spooled in conventional manner after being withdrawn from the bath and are highly stretched.

The stretched fibers are then spooled upon perforated rollers and are subjected to a treatment with steam having a temperature of C. whereby the solvent contained in the fibers is expelled. The fibers thus produced are strongly dulled and show the desired roughening.

Iclaim:

1. Method of roughening and dulling polyethylene terephthalate fibers which comprises spinning a molten mass of solvent-containing polyethylene terephthalate into a fiber which retains a portion of said solvent, the solvent in said molten mass being present in an amount of from 5% to 30%, passing the spun fiber through a bath wherein the aforesaid solvent is extracted from a surface layer of the fiber, stretching the so treated fiber, and subjecting the stretched fiber to the action of superheated steam to expel the residual solvent.

2. Method of roughening and dulling polyethylene terephthalate fibers which comprises spinning a molten mass of solvent-containing polyethylene terephthalate into a fiber which retains a portion of said solvent, the solvent in said molten mass being present in an amount of from 5% to 30%, passing the spun fiber through a short air gap into a cold organic liquid that extracts solvent from a surface layer of the fiber, then stretching the so treated fiber, and then subjecting the stretched fiber to the action of superheated steam to expel the residual solvent.

3. Process of roughening and dulling polyethylene terephthalate fiber which comprises spinning a molten mass of solvent-containing polyethylene terephthalate into a fiber which retains a portion of said solvent, the solvent in said molten mass being present in an amount of from 5% to 30%, extracting the solvent retained in the freshly spun fiber from a surface layer of the fiber by a cold organic solvent, stretching the thus treated fiber, and then subjecting the stretched fiber to the action of superheated steam to expel the residual solvent.

4. Process in accordance with claim. 3 wherein the cold organic liquid is carbon tetrachloride.

5. Process in accordance with claim 3 wherein the cold organic liquid is tetrachloroethylene.

6. Process in accordance with claim 3 wherein the cold organic liquid is acetone.

7. Process in accordance with claim 3 wherein the cold organic liquid is tetrahydronaphthalene.

References Cited in the file of this patent UNITED STATES PATENTS 2,157,117 Miles May 9, 1939 2,214,442 Spanagel Sept. 10, 1940 2,404,727 Houtz July 23, 1946 2,556,295 Pace June 12, 1951 2,558,730 Cresswell July 3, 1951 2,604,689 Hebeler July 29, 1952 FOREIGN PATENTS 603,840 Great Britain June 23, 1948 610,183 Great Britain Oct. 12, 1948 

1. METHOD OF ROUGHENING AND DULLING POLYETHYLENEENE TEREPHTHALATE FIBERS WHICH COMPRISES SPINNING A MOLTEN MASS OF SOLVENT-CONTAINING POLYETHYLEN TEREPHTHALATE INTO A FIBER WHICH RETAINS A PORTION OF SAID SOLVENT, THE SOLVENT IN SAID MOLTEN MASS BEING PRESENT IN AN AMOUNT OF FROM 5% TO 30%, PASSING THE SPUN FIBER THROUGH A BATH WHEREIN THE AFORESAID SOLVENT IS EXTRACTED FROM A SURFACE LAYER OF THE FIBER, STRETCHING THE SO TREATED FIBER, AND SUBJECTING THE STRETCHED FIBER TO THE ACTION OF SUPERHEATED STEAM TO EXPEL THE RESIDUAL SOLVENT. 